I don't see any reason why the X-Ex would drop out of the lineup. It makes sense even with the addition of the X-Tx series.

From a pure design standpoint I favor the rangefinder form factor. It's cleaner and more elegant to my eye. I see no reason why Fuji couldn't design a rangefinder style X mount cam with the larger EVF. it would be the X-Pro1 with the new EVF instead of the large hybrid OVF/EVF it has now. Would that be an X-Pro2 or an X-E3? My guess is that's what Fuji is figuring out right now. Either way my money is on Fuji continuing on with the rangefinder form factor. They've established it as a big part of their brand identity. The addition of the X-T1 doesn't change that.